Add private save-behind and draw-behind methods to canvas.HEADp9.0

The draw-behind  is a variant of drawPaint but is automatically clipped
to the bounds of the most recent saveBehind buffer (axis-aligned bounds).

No public exposure outside of the Android framework.

Impl is pretty simple (its a variant of drawPaint)
- find the most recent saveBehind device bounds
- if there is none, draw nothing, else
  - temporarily intersect the device's clip with that bounds
  - drawPaint
  - restore the clip

This patches did not apply cleanly and have been updated to compile
with a previous version of Skia. It was cherry-picked from the
following 3 Skia commits:
148b7fd3ad9c29dec0052de624c26ff291ef8f0a
d567408362bf7847d6000f6786f9a7b2c9d0b88b
9adc82c73df0ef25b708cae8aa48ef9c39ed4c67

Bug: 129117085
Test: None
Change-Id: I291f57885de6e95f749bf5cdb70ac16a5781ffb1

1 files changed, 3 insertions, 0 deletions

diff --git a/include/core/SkRect.h b/include/core/SkRect.h
index f9a5bff4ff..dd66d75076 100644
--- a/include/core/SkRect.h
+++ b/include/core/SkRect.h
@@ -154,6 +154,9 @@ struct SK_API SkIRect {
     */
     int32_t y() const { return fTop; }
 
+    // Experimental
+    SkIPoint topLeft() const { return {fLeft, fTop}; }
+
     /** Returns span on the x-axis. This does not check if SkIRect is sorted, or if
         result fits in 32-bit signed integer; result may be negative.